This change is needed (as far as i can tell), in order to use stdin and stdout as the interface for the debug adapter. I have tested with vscode and confirmed that this fixes the following errors:

• Input was not being read, as there is no newline seperator after the content.
• Output was not being flushed (on my machine), likely because there is no newline.

I decided the easiest thing to do was to combine the Sep and Content states, and read the content based on content-length, while keeping the rest of the loop based on read_line.

I'm still new to rust and what is considered best practices, so please point any mistakes or inefficiencies (especially error handling trips me up)

Edit: The reason the testinput file works is because read_line also terminates at EOF.